From: Laurent Dufour <ldufour@linux.ibm.com>
To: Jerome Glisse <jglisse@redhat.com>
Cc: jack@suse.cz, sergey.senozhatsky.work@gmail.com,
peterz@infradead.org, Will Deacon <will.deacon@arm.com>,
mhocko@kernel.org, linux-mm@kvack.org, paulus@samba.org,
Punit Agrawal <punitagrawal@gmail.com>,
hpa@zytor.com, Michel Lespinasse <walken@google.com>,
Alexei Starovoitov <alexei.starovoitov@gmail.com>,
Andrea Arcangeli <aarcange@redhat.com>,
ak@linux.intel.com, Minchan Kim <minchan@kernel.org>,
aneesh.kumar@linux.ibm.com, x86@kernel.org,
Matthew Wilcox <willy@infradead.org>,
Daniel Jordan <daniel.m.jordan@oracle.com>,
Ingo Molnar <mingo@redhat.com>,
David Rientjes <rientjes@google.com>,
paulmck@linux.vnet.ibm.com, Haiyan Song <haiyanx.song@intel.com>,
npiggin@gmail.com, sj38.park@gmail.com, dave@stgolabs.net,
kemi.wang@intel.com, kirill@shutemov.name,
Thomas Gleixner <tglx@linutronix.de>,
zhong jiang <zhongjiang@huawei.com>,
Ganesh Mahendran <opensource.ganesh@gmail.com>,
Yang Shi <yang.shi@linux.alibaba.com>,
Mike Rapoport <rppt@linux.ibm.com>,
linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org,
Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
vinayak menon <vinayakm.list@gmail.com>,
akpm@linux-foundation.org, Tim Chen <tim.c.chen@linux.intel.com>,
haren@linux.vnet.ibm.com
Subject: Re: [PATCH v12 01/31] mm: introduce CONFIG_SPECULATIVE_PAGE_FAULT
Date: Tue, 23 Apr 2019 17:21:37 +0200 [thread overview]
Message-ID: <bcb29b68-0dd4-92a7-4f7e-1cb009233ed7@linux.ibm.com> (raw)
In-Reply-To: <20190418214721.GA11645@redhat.com>
Le 18/04/2019 à 23:47, Jerome Glisse a écrit :
> On Tue, Apr 16, 2019 at 03:44:52PM +0200, Laurent Dufour wrote:
>> This configuration variable will be used to build the code needed to
>> handle speculative page fault.
>>
>> By default it is turned off, and activated depending on architecture
>> support, ARCH_HAS_PTE_SPECIAL, SMP and MMU.
>>
>> The architecture support is needed since the speculative page fault handler
>> is called from the architecture's page faulting code, and some code has to
>> be added there to handle the speculative handler.
>>
>> The dependency on ARCH_HAS_PTE_SPECIAL is required because vm_normal_page()
>> does processing that is not compatible with the speculative handling in the
>> case ARCH_HAS_PTE_SPECIAL is not set.
>>
>> Suggested-by: Thomas Gleixner <tglx@linutronix.de>
>> Suggested-by: David Rientjes <rientjes@google.com>
>> Signed-off-by: Laurent Dufour <ldufour@linux.ibm.com>
>
> Reviewed-by: Jérôme Glisse <jglisse@redhat.com>
Thanks Jérôme.
> Small question below
>
>> ---
>> mm/Kconfig | 22 ++++++++++++++++++++++
>> 1 file changed, 22 insertions(+)
>>
>> diff --git a/mm/Kconfig b/mm/Kconfig
>> index 0eada3f818fa..ff278ac9978a 100644
>> --- a/mm/Kconfig
>> +++ b/mm/Kconfig
>> @@ -761,4 +761,26 @@ config GUP_BENCHMARK
>> config ARCH_HAS_PTE_SPECIAL
>> bool
>>
>> +config ARCH_SUPPORTS_SPECULATIVE_PAGE_FAULT
>> + def_bool n
>> +
>> +config SPECULATIVE_PAGE_FAULT
>> + bool "Speculative page faults"
>> + default y
>> + depends on ARCH_SUPPORTS_SPECULATIVE_PAGE_FAULT
>> + depends on ARCH_HAS_PTE_SPECIAL && MMU && SMP
>> + help
>> + Try to handle user space page faults without holding the mmap_sem.
>> +
>> + This should allow better concurrency for massively threaded processes
>
> Is there any case where it does not provide better concurrency ? The
> should make me wonder :)
Depending on the VMA's type, it may not provide better concurrency.
Indeed only anonymous mapping are managed currently. Perhaps this should
be mentioned here, is it ?
>> + since the page fault handler will not wait for other thread's memory
>> + layout change to be done, assuming that this change is done in
>> + another part of the process's memory space. This type of page fault
>> + is named speculative page fault.
>> +
>> + If the speculative page fault fails because a concurrent modification
>> + is detected or because underlying PMD or PTE tables are not yet
>> + allocated, the speculative page fault fails and a classic page fault
>> + is then tried.
>> +
>> endmenu
>> --
>> 2.21.0
>>
>
next prev parent reply other threads:[~2019-04-23 15:23 UTC|newest]
Thread overview: 98+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-16 13:44 [PATCH v12 00/31] Speculative page faults Laurent Dufour
2019-04-16 13:44 ` [PATCH v12 01/31] mm: introduce CONFIG_SPECULATIVE_PAGE_FAULT Laurent Dufour
2019-04-18 21:47 ` Jerome Glisse
2019-04-23 15:21 ` Laurent Dufour [this message]
2019-04-16 13:44 ` [PATCH v12 02/31] x86/mm: define ARCH_SUPPORTS_SPECULATIVE_PAGE_FAULT Laurent Dufour
2019-04-18 21:48 ` Jerome Glisse
2019-04-16 13:44 ` [PATCH v12 03/31] powerpc/mm: set ARCH_SUPPORTS_SPECULATIVE_PAGE_FAULT Laurent Dufour
2019-04-18 21:49 ` Jerome Glisse
2019-04-16 13:44 ` [PATCH v12 04/31] arm64/mm: define ARCH_SUPPORTS_SPECULATIVE_PAGE_FAULT Laurent Dufour
2019-04-16 14:27 ` Mark Rutland
2019-04-16 14:31 ` Laurent Dufour
2019-04-16 14:41 ` Mark Rutland
2019-04-18 21:51 ` Jerome Glisse
2019-04-23 15:36 ` Laurent Dufour
2019-04-23 16:19 ` Mark Rutland
2019-04-24 10:34 ` Laurent Dufour
2019-04-16 13:44 ` [PATCH v12 05/31] mm: prepare for FAULT_FLAG_SPECULATIVE Laurent Dufour
2019-04-18 22:04 ` Jerome Glisse
2019-04-23 15:45 ` Laurent Dufour
2019-04-16 13:44 ` [PATCH v12 06/31] mm: introduce pte_spinlock " Laurent Dufour
2019-04-18 22:05 ` Jerome Glisse
2019-04-16 13:44 ` [PATCH v12 07/31] mm: make pte_unmap_same compatible with SPF Laurent Dufour
2019-04-18 22:10 ` Jerome Glisse
2019-04-23 15:43 ` Matthew Wilcox
2019-04-23 15:47 ` Laurent Dufour
2019-04-16 13:44 ` [PATCH v12 08/31] mm: introduce INIT_VMA() Laurent Dufour
2019-04-18 22:22 ` Jerome Glisse
2019-04-16 13:45 ` [PATCH v12 09/31] mm: VMA sequence count Laurent Dufour
2019-04-18 22:48 ` Jerome Glisse
2019-04-19 15:45 ` Laurent Dufour
2019-04-22 15:51 ` Jerome Glisse
2019-04-16 13:45 ` [PATCH v12 10/31] mm: protect VMA modifications using " Laurent Dufour
2019-04-22 19:43 ` Jerome Glisse
2019-04-16 13:45 ` [PATCH v12 11/31] mm: protect mremap() against SPF hanlder Laurent Dufour
2019-04-22 19:51 ` Jerome Glisse
2019-04-23 15:51 ` Laurent Dufour
2019-04-16 13:45 ` [PATCH v12 12/31] mm: protect SPF handler against anon_vma changes Laurent Dufour
2019-04-22 19:53 ` Jerome Glisse
2019-04-16 13:45 ` [PATCH v12 13/31] mm: cache some VMA fields in the vm_fault structure Laurent Dufour
2019-04-22 20:06 ` Jerome Glisse
2019-04-16 13:45 ` [PATCH v12 14/31] mm/migrate: Pass vm_fault pointer to migrate_misplaced_page() Laurent Dufour
2019-04-22 20:09 ` Jerome Glisse
2019-04-16 13:45 ` [PATCH v12 15/31] mm: introduce __lru_cache_add_active_or_unevictable Laurent Dufour
2019-04-22 20:11 ` Jerome Glisse
2019-04-16 13:45 ` [PATCH v12 16/31] mm: introduce __vm_normal_page() Laurent Dufour
2019-04-22 20:15 ` Jerome Glisse
2019-04-16 13:45 ` [PATCH v12 17/31] mm: introduce __page_add_new_anon_rmap() Laurent Dufour
2019-04-22 20:18 ` Jerome Glisse
2019-04-16 13:45 ` [PATCH v12 18/31] mm: protect against PTE changes done by dup_mmap() Laurent Dufour
2019-04-22 20:32 ` Jerome Glisse
2019-04-24 10:33 ` Laurent Dufour
2019-04-16 13:45 ` [PATCH v12 19/31] mm: protect the RB tree with a sequence lock Laurent Dufour
2019-04-22 20:33 ` Jerome Glisse
2019-04-16 13:45 ` [PATCH v12 20/31] mm: introduce vma reference counter Laurent Dufour
2019-04-22 20:36 ` Jerome Glisse
2019-04-24 14:26 ` Laurent Dufour
2019-04-16 13:45 ` [PATCH v12 21/31] mm: Introduce find_vma_rcu() Laurent Dufour
2019-04-22 20:57 ` Jerome Glisse
2019-04-24 14:39 ` Laurent Dufour
2019-04-23 9:27 ` Peter Zijlstra
2019-04-23 18:13 ` Davidlohr Bueso
2019-04-24 7:57 ` Laurent Dufour
2019-04-16 13:45 ` [PATCH v12 22/31] mm: provide speculative fault infrastructure Laurent Dufour
2019-04-22 21:26 ` Jerome Glisse
2019-04-24 14:56 ` Laurent Dufour
2019-04-24 15:13 ` Jerome Glisse
2019-04-16 13:45 ` [PATCH v12 23/31] mm: don't do swap readahead during speculative page fault Laurent Dufour
2019-04-22 21:36 ` Jerome Glisse
2019-04-24 14:57 ` Laurent Dufour
2019-04-16 13:45 ` [PATCH v12 24/31] mm: adding speculative page fault failure trace events Laurent Dufour
2019-04-16 13:45 ` [PATCH v12 25/31] perf: add a speculative page fault sw event Laurent Dufour
2019-04-16 13:45 ` [PATCH v12 26/31] perf tools: add support for the SPF perf event Laurent Dufour
2019-04-16 13:45 ` [PATCH v12 27/31] mm: add speculative page fault vmstats Laurent Dufour
2019-04-16 13:45 ` [PATCH v12 28/31] x86/mm: add speculative pagefault handling Laurent Dufour
2019-04-16 13:45 ` [PATCH v12 29/31] powerpc/mm: add speculative page fault Laurent Dufour
2019-04-16 13:45 ` [PATCH v12 30/31] arm64/mm: " Laurent Dufour
2019-04-16 13:45 ` [PATCH v12 31/31] mm: Add a speculative page fault switch in sysctl Laurent Dufour
2019-04-22 21:29 ` [PATCH v12 00/31] Speculative page faults Michel Lespinasse
2019-04-23 9:38 ` Peter Zijlstra
2019-04-24 7:33 ` Laurent Dufour
2019-04-27 1:53 ` Michel Lespinasse
2019-04-23 10:47 ` Michal Hocko
2019-04-23 12:41 ` Matthew Wilcox
2019-04-23 12:48 ` Peter Zijlstra
2019-04-23 13:42 ` Michal Hocko
2019-04-24 18:01 ` Laurent Dufour
2019-04-27 6:00 ` Michel Lespinasse
2019-04-23 11:35 ` Anshuman Khandual
2019-06-06 6:51 ` Haiyan Song
2019-06-14 8:37 ` Laurent Dufour
2019-06-14 8:44 ` Laurent Dufour
2019-06-20 8:19 ` Haiyan Song
2020-07-06 9:25 ` Chinwen Chang
2020-07-06 12:27 ` Laurent Dufour
2020-07-07 5:31 ` Chinwen Chang
2020-12-14 2:03 ` Joel Fernandes
2020-12-14 9:36 ` Laurent Dufour
2020-12-14 18:10 ` Joel Fernandes
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